Readiness probe failed: HTTP probe failed with statuscode: 503 port 8008 in POD

Hi,
Following this quick Guide, as soon as we deploy postgresql, Pod status is went to not ready state.

  Normal   Scheduled         7m42s                   default-scheduler  Successfully assigned default/acid-minimal-cluster-1 to ip-172-31-6-72.us-east-2.compute.internal
  Normal   Pulled            7m42s                   kubelet            Container image "registry.opensource.zalan.do/acid/spilo-14:2.1-p6" already present on machine
  Normal   Created           7m42s                   kubelet            Created container postgres
  Normal   Started           7m42s                   kubelet            Started container postgres
  Warning  Unhealthy         **2m52s (x13 over 6m42s)  kubelet            Readiness probe failed: HTTP probe failed with statuscode: 503**

Manual deployment setup on Kubernetes

First, clone the repository and change to the directory

git clone https://github.com/zalando/postgres-operator.git
cd postgres-operator

apply the manifests in the following order

kubectl create -f manifests/configmap.yaml # configuration
kubectl create -f manifests/operator-service-account-rbac.yaml # identity and permissions
kubectl create -f manifests/postgres-operator.yaml # deployment
kubectl create -f manifests/api-service.yaml # operator API to be used by UI

create a Postgres cluster

kubectl create -f manifests/minimal-postgres-manifest.yaml

\NAME                                     READY   STATUS    RESTARTS   AGE     IP             NODE                                        NOMINATED NODE   READINESS GATES
pod/acid-minimal-cluster-0               0/1     Running   0          9m18s   10.244.2.128   ip-172-31-6-72.us-east-2.compute.internal   <none>           <none>
pod/acid-minimal-cluster-1               0/1     Running   0          9m11s   10.244.2.129   ip-172-31-6-72.us-east-2.compute.internal   <none>           <none>
pod/postgres-operator-6b8c5c9656-tr6zf   1/1     Running   0          10m     10.244.2.127   ip-172-31-6-72.us-east-2.compute.internal   <none>           <none>

NAME                                  TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)    AGE     SELECTOR
service/acid-minimal-cluster          ClusterIP   10.96.128.61    <none>        5432/TCP   9m19s   <none>
service/acid-minimal-cluster-config   ClusterIP   None            <none>        <none>     9m16s   <none>
service/acid-minimal-cluster-repl     ClusterIP   10.96.166.233   <none>        5432/TCP   9m19s   application=spilo,cluster-name=acid-minimal-cluster,spilo-role=replica
service/kubernetes                    ClusterIP   10.96.0.1       <none>        443/TCP    10m     <none>
service/postgres-operator             ClusterIP   10.96.27.45     <none>        8080/TCP   10m     name=postgres-operator

NAME                                READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS          IMAGES                                                       SELECTOR
deployment.apps/postgres-operator   1/1     1            1           10m   postgres-operator   registry.opensource.zalan.do/acid/postgres-operator:v1.8.2   name=postgres-operator

NAME                                           DESIRED   CURRENT   READY   AGE   CONTAINERS          IMAGES                                                       SELECTOR
replicaset.apps/postgres-operator-6b8c5c9656   1         1         1       10m   postgres-operator   registry.opensource.zalan.do/acid/postgres-operator:v1.8.2   name=postgres-operator,pod-template-hash=6b8c5c9656

NAME                                    READY   AGE     CONTAINERS   IMAGES
statefulset.apps/acid-minimal-cluster   0/2     9m19s   postgres     registry.opensource.zalan.do/acid/spilo-14:2.1-p6

NAME                                            TEAM   VERSION   PODS   VOLUME   CPU-REQUEST   MEMORY-REQUEST   AGE     STATUS
postgresql.acid.zalan.do/acid-minimal-cluster   acid   14        2      1Gi                                     9m19s   Running 

Start by reproducing the deployment from manifests/minimal-postgres-manifest.yaml and inspect the readiness probe behavior of registry.opensource.zalan.do/acid/spilo-14:2.1-p6 on port 8008. Compare the pod events and cluster status with the operator and Kubernetes configuration; done means identifying the cause of the 503 and confirming that the PostgreSQL pods become Ready.